Customers getting Errors

Customers getting Errors

I thought at first it was a fluke, but more and more customers are getting this error and cannot finish their order proces. I've changed nothing so there must be some forgotten postal codes in the software? Here is the message they get:

""Our apologies. We are not currently set up to ship products to your country or postal code. Please, make sure you have entered a valid postal code, it is possible we can negotiate a shipping rate for you, so please contact us directly for assistance."